454 Mag Bravo I gasket found in transom exhaust...need help.

r1elkins

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Joined
Sep 18, 2017
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8
Hello everyone. I recently bought an 89 Cobalt 222 Condurre with a 454 Mag Bravo I. I bought it out of state, so when I returned to Colorado I had to have the boat inspected (zebra mussels) before I went out on the lake for the first time. The inspector looked into the transom exhaust and said I had a mouse nest in there, but not to worry it would wash out on the lake. Took the boat around the lake a few times, called it good and went home for the day. I then looked into the transom exhaust to see if the mouse nest was gone...it wasn't. Well come to find out, it wasn't a mouse nest at all. It was some sort of rubber-lined metal gasket that was wedged in there and had built up carbon around it. I removed the prop and began removing the debris. Please see attached picture. I have no idea what the gasket is or the metal clip. I looked through the Mercruiser manual and tried to identify the gasket with no luck. Any help would be appreciated.

Thanks in advance,

​Jason

https://www.flickr.com/photos/159442334@N04/shares/r46nv3
 

r1elkins

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Joined
Sep 18, 2017
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r46nv3
I am also trying to upload the picture but it's saying I'm not authorized to upload attachments. How many posts do I have to have for that to be enabled?
 

GA_Boater

Honorary Moderator Emeritus
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May 24, 2011
Messages
49,038
Welcome aboard.

Click the Forum Help link in my sig and look at the photo tutorial.

Replace the exhaust shutters. They fall out like that when the motor is overheated and the rubber parts of the shutter melt. There are two shutters in the exhaust at the top of each side of the Y-pipe.
shutters.PNG
 

r1elkins

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Joined
Sep 18, 2017
Messages
8
Thanks GA for the quick reply. I was following the photo tutorial. It said I needed 3 posts to upload pictures, which I did. I do not see the photo button on the left side of the ribbon bar. No worries, I created a Flickr account and am able to embed images now. I'm sure this will be one of many questions I have. :) My first repair...how exciting!

Much appreciated.

Jason
 

r1elkins

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Sep 18, 2017
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Do you think having this shutter stuck in there would cause the engine not to reach max RPMs? Reason I ask is because when I was on the lake I notice the engine would not go above 3400 RPMs and max speed was 38 mph. I figured it was because I needed to install high altitude metering rods and possibly a new prop.
 

GA_Boater

Honorary Moderator Emeritus
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May 24, 2011
Messages
49,038
Jam a potato onto the end of your car exhaust pipe - Same thing. Restricted exhaust can reduce power.
 

tpenfield

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Staff member
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Jul 18, 2011
Messages
18,137
Mice are always leaving their exhaust shutters where they shouldn't . :D

I got a couple of exhaust shutters on my engines that are un-accounted for . . . Hopefully I will find the remains of them either in the y-tube or the outdrive when I pull things apart at the end of the season.
 
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